This invention relates to quick disconnect couplings, and, more particularly, to a female quick disconnect coupling which requires distinctly different forces to connect and disconnect a male coupling.
Quick disconnect couplings are used, for example, to connect hydraulic fluid line hoses. When the male and female couplings on the ends of a pair of hoses are connected, fluid can flow through the hoses. When the couplings are disconnected, valves within the couplings close and prevent fluid from escaping.
Quick disconnect couplings are so named because the male and female couplings can be quickly connected and disconnected by simple pushing and pulling forces. In many applications it is desirable to have a relatively low push force to connect the couplings and a relatively high pull force to disconnect the couplings. This is desirable, for example, so that normal movement of the hoses and slight pulling forces on the hoses will not accidentally disconnect the couplings. However, a severe pull will disconnect the couplings and prevent tensile failure to the hoses.
U.S. Pat. No. 4,240,466 describes a coupling which provides two different connecting and disconnecting forces. However, the present invention provides a much shorter, more compact design which uses fewer parts. A female coupling includes an outer sleeve and a tubular housing which is slidably mounted within the sleeve. A radially inwardly extending locking portion on the sleeve is engageable with locking balls on the housing, and the housing is movable between a coupled position, in which the locking balls are forced inwardly by the sleeve to lock a male coupling, and partially coupled and partially uncoupled positions in which the locking balls are free to move outwardly. A pair of coil springs are mounted between the housing and the sleeve. Only one of the coil springs is compressed when the housing moves from its uncoupled position to its partially coupled position to provide a relatively low connecting force, and both springs are compressed when the housing moves from its coupled position to its partially uncoupled position to provide a relatively high disconnecting force. The springs return the housing to its coupled position when the connecting or disconnecting force is released.